Vacuum tube



s. HOLST AND sroos'nznnuls. VACUUM TUBE.

APPLICATION FILED MAR. 30, 192]- Patented Mar. 28, 1922.

' small UNITED STATES PATENT OFFICE.

GILLES HOLST AND EK KO OOSTERHUIS, OF EINDHOVEN, NETHERLANDS, ASSIGNORS TO NAAMLOOZE VENNOOTSCHAP PHILIPS GLOEILAMPEN-FABRIKEN. OF EIND- HOVEN, NETHERLANDS, A LIMITED LIABILITY COMPANY OF THE NETHERLANDS.

VACUUM TUBE.

Application filed March 30, 1921.

tion.

It is known, that the gas contents of vacuum tubes, such as Rt'mtgen tubes or Geissler tubes, or tubes for the Moore light, etc., disappear undefithe influence of the electric discharge. The tube thereby becomes harder, the passage of the current becomes more diflicult and finally stops altogether. Therefore, several kinds of apparatus have been devised to automatically renew or complete the gas in the tube. ()ne of these apparatus is the Bauer valve. It consists of a glass capillary tube. partly filled with mercury. To this capillary tube a small side tube is attached, containing a porous plug. With a small air-pump, the mercury may be forced past the porous plug, so that air passes into the vacuum tube. This device, therefore, is not automatic and is only able to force air into the tube.

The present invention relates to a similar device in which however, the filling can take place automatically, as soon as the hardness of the tube exceeds a definite degree, and by which anygas may be brought into the vacuum tube.

In the accompanying drawings,

Figure 1 is a section of a Bauer valve,

Figure 2 is a section of a construction according to the invention, and

Figure 3 shows diagrammatically the apparatus according to the invention, connected to a. vacuum tube.

Figure 4 is a fragment of Fig. 2-. showing a modification.

The Bauer valve shown in Fig. 1 comprises a tubular vessel d having at b a connec- Specifieation of Letters Patent.

Patented Mar. 28, 1922.

Serial No. 457,146.

tion to the vacuum tube, with a mercury tube is sealed into it at m with its end n open Y to the atmosphere, and at g a branch tube opening into d and sealed by a porous plug 7) which is impermeable to mercury but permeable to gas. \Vith a suflicient vacuum in the vacuum tube, the mercury is forced down by the atmospheric pressure until it uncovers the plug, whereupon air enters through the porous plug into (I and through 7) into the vacuum tube.

The apparatus according to this invention (see Fig. 2) consists of a gas reservoir a. in which there is a heating means whereby the gas in a may be heated by an electric current. The heating device may consist for example of two electrodes (as shown in Fig. 2), or of an incandescent filament (as shown in Fig. 4). Vhen the current passes, the

gas will expand and thereby press the mercury column is in the capillary tube a downwards. At 72 is a porous plug impermeable to mercury but permeable to gas. 'hen the pressure in or becomes so high that the mercury is forced below 2 a small quantity of gas will diffuse through the porous plug and .pass through the tube b into the vacuum tube.

To obtain automatic working one may proceed in any 'usual way.

The Rontgen tube shown in Figure 3 is connected to a source of electricity. One of the electrodes in a is connected to the anode, the other is connected to a wire or a small bar which is placed at a suitable distance from the cathode. As soon as the Rontgen tube becomes too hard, the electric current will ass through a and heat the as therein. he mercury is forced past t e porous plug, so that a small quantity of gas difl'uses into the Rontgen tube. Thereby the latter becomes softer and the discharge will again take place in the normal way.

An advantage of the device described is that any desired gas can be passed into the vacuum tube because the reservoir (1 is completely closed.

\Vhat we claim is 1. A device for introducing gas in a vacuum tube, comprising a reservoir containing gas, having within it means for electrically heating the gas and a mercury tube connecting with the reservoir and having a porous plug connection with the interior of the vacuum tube.

2. A device for introducing gas in a vacuum tube, comprisin a reservoirc containing gas, having within it two electrodes for heating the gas, and a mercury tube connecting with the reservoir and having a porous plug connection with the interior of the vacuum tube.

In witness whereof, we have hereunto signed our names in the presence of two sub- SCI'lblIlg witnesses.

GILLES HOLST, EKKO OOSTERHUIS. 'itnexes:

Hrzzmmous J AMPS, ALPHONSO on BRUT.

Certificate of Correction.

It is hereby certified that the assignee in Letters Patent No. 1,410,756, granted March 28, 1922, upon the application of Gilles Holst and Ekko Oosterhuia, of Eindhoven, Netherlands, for an improvement in Vacuum Tubes) was erroneously described and specified as Naamlooze vennootschap Philips Gloeilampen- Fabriken, ef Eindhoiren, Netheriands, a. Limited Liability Company of the Netherlands. whereas said assignee should have been described and specified as Naa'mlooze Vcnnaotscbap Philips GIoeilampen-Fa-brieken, of Ez'ndhoven, Netherlands, a Limited Liability] Company of the i'i'ethcrlfmda, as shown by the records of assignments in this ofiice; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case inthe Patent Offie.

Signed and sealed this 20th day of June, A. 1)., 1922.

KARL FENNING,

[sun] Acti'rug Commissioner of Patents. 

